Don't be misled by the pleasant air temperatures because the water temperature at Ontonagon is much colder than the air today. Surfers will need a good quality sealed winter wetsuit, a neoprene hood, gloves and boots. Feeling much warmer out of the water than in the sea today.

Map of current United States
Surface Water Temperatures based on measurements from oceanographic satellites

Map of current United States
Sea Water Temperature Anomalies
(compared with long term averages at this time of year)

(click thumbnails to expand)

Below is a graph of Historical Sea Surface Temperature for Ontonagon. This has been derived from analysis of two decades of oceanographic satellite measurements of nearby open water. We have calculated the average water temperature variation around the year as well as the extremes that have been observed on each date.

All of the graphs for the surf breaks presented on Surf-Forecast.com are on the same scale to enable comparison between locations around the world.

Ontonagon sea temperatures peak in the range 12 to 19°C (54 to 66°F) on around the 14th of August and are at their lowest on about the 22nd of March, in the range 1 to 2°C (34 to 36°F). The warmest seasonal sea temperatures at Ontonagon in mid August lend themselves to a 4/3mm wetsuit or a 3/2mm suit and 3mm neoprene boots. The lowest sea temperatures at Ontonagon mean that you will need a flexible 6/5/4mm wetsuit or a well fitting 5/4mm wetsuit with gloves and 5mm neoprene booties and a hood to surf here in the second half of March.

Actual sea surface water temperatures close to shore at Ontonagon can vary by several degrees compared with these open water averages. This is especially true after heavy rain, close to river mouths or after long periods of strong offshore winds. Offshore winds cause colder deep water to replace surface water that has been warmed by the sun. Air temperature, wind-chill and sunshine should also be considered before deciding on the kind of wetsuit needed to stay warm when surfing at Ontonagon. Refer to our detailed weather forecasts for this information.